Fix PHP 8.5 deprecation warning (#81)

* chore(ci): add php 8.5

* chore(ci): bump dependencies

* fix: use empty string as array key explicitly because using null is deprecated in php 8.5

Author: W0rma

.github/workflows/main.yml

@@ -11,16 +11,20 @@ jobs:
 
     strategy:
       matrix:
-        php: [8.1, 8.2, 8.3, 8.4]
+        php: [8.1, 8.2, 8.3, 8.4, 8.5]
 
     steps:
     - name: Checkout code
-      uses: actions/checkout@v4
+      uses: actions/checkout@v6
 
     - name: Setup PHP
       uses: shivammathur/setup-php@v2
       with:
         php-version: ${{ matrix.php }}
+        # this ini directive seems to be off by default in PHP 8.5
+        # see https://github.com/php/php-src/issues/20279
+        # enable it because codeception relies on it.
+        ini-values: register_argc_argv=1
 
     - name: Validate composer.json and composer.lock
       run: composer validate

src/Codeception/Lib/InnerBrowser.php

@@ -1054,7 +1054,7 @@ protected function getFormFor(Crawler $node): SymfonyForm
             $this->fail('The selected node is not a form and does not have a form ancestor.');
         }
 
-        $identifier = $form->attr('id') ?: $form->attr('action');
+        $identifier = $form->attr('id') ?: $form->attr('action') ?? '';
         if (!isset($this->forms[$identifier])) {
             $this->forms[$identifier] = $this->getFormFromCrawler($form);
         }